Determination of susceptible areas to water erosion in the Hervi watershed

In order to protect soil and water resources should be identified erodible areas of watersheds, to be able to prevent land degradation and to control erosion in the form of soil conservation planning or watershed management. Therefore, the present study aimed to classification and delineation of susceptible areas to water erosion in the Hervi watershed using Hjulstrom curve, has been conducted. Increasing of accuracy, speed and facility of spatial achievement, using GIS technology, are advantages of the present study. In this study, were separated 10 sub-watersheds based on the feeding levels of streams. Spatial variability of soil properties in sub-watersheds, such as texture and the mean diameter size of the particles using hydrometer method were measured; also the maximum potential velocity of outlet in sub-watersheds based on the characteristics of each sub-watershed were calculated. Then, status of erosion and sediment in watersheds and sub-watersheds was studied using Hjulstrom curve (based on the mean diameter size of sediment particles and the maximum potential velocity of outlet), and was comparatively classified in term of erodibility. Finally, delineation map of susceptible regions to water erosion in the study area were obtained. The results revealed that the upstream and side areas of the watershed including: Sub-watershed No.4 (8.94% of the land), has very high erodibility, and Sub-watersheds No.1 and No.9 (36.94% of the land) have high erodibility. These areas are steep and often devoid of vegetation or have poor vegetation (such as poor pastures and rain-fed farming); so, it is necessary a proper strategy to prevent further erosion.